AAAS AMA: We're a team of researchers who have just published an assessment quantifying the global sources and losses of methane, a powerful greenhouse gas, and their role in contributing to a recent and surprisingly rapid increase in the atmosphere. Ask us anything!

Abstract

Hi! We're Drs. Ben Poulter, Rob Jackson and Pep Canadell -- we study the global carbon cycle and try to balance budgets of carbon dioxide (CO2) and methane (CH4) by accounting for all known sources and losses, or sinks, from natural and human-related activities. Methane is a greenhouse gas 28 times more powerful than CO2 on a 100-year time horizon and has increased over 150% since the industrial revolution. Our budget is intended to answer questions such as: What are the sources of methane that are contributing to a renewed rate of growth that began in 2007 and where are they located? Has the rate of loss of methane decreased in the past decade? How has a switch in fossil fuel activities from coal-based to oil and gas extraction contributed to the increase in atmospheric methane? What is the role of agriculture (livestock and rice cultivation) versus wetlands in the growth rate of methane concentrations? And, what does the recent increase in methane concentrations tell us about projections used by the Intergovernmental Panel on Climate Change?

A bit about our team:

Ben Poulter (http://science.gsfc.nasa.gov/sed/bio/benjamin.poulter) is a Research Scientist in the Earth Sciences Division at NASA Goddard Space Flight Center. He uses ecological models and remote sensing to understand the role of vegetation in the terrestrial carbon cycle and how humans and climate change have modified CO2 and CH4 fluxes.

Rob Jackson (https://earth.stanford.edu/rob-jackson) is the Michelle and Kevin Douglas Provostial Professor and Senior Fellow at the Woods Institute for the Environment and at the Precourt Institute for Energy at Stanford University, and the Chair of the Global Carbon Project. Rob's lab seeks to produce the building blocks of basic scientific knowledge and to use that knowledge to guide policy solutions for global warming, energy extraction, and other environmental issues.

Pep Canadell (http://www.globalcarbonproject.org/who_is_who/pep_canadell.htm) is the Executive Director for the Global Carbon Project and a Research Scientist at CSIRO in Australia. He focuses on collaborative and integrative research to study global and regional aspects of the carbon cycle, the size and vulnerability of earth carbon pools, and pathways to climate stabilization

The global CH4 budget

What the increase in CH4 means for the future

Download and to visualize the datasets

We will be back at 2 pm Pacific Coast time, and would love to answer your questions!

Hi, thanks for showing up and answering questions.

  1. How much is the release of CH4 from melting polar ice contributing to the overall spike, if any? I find it strange that the area we're focused on is tropical.

  2. What strategy among the ones you listed (wellpad gas leak removal, coal mine flaring, bio-digester adoption, covering landfills) do you think is the most viable and attainable to start with? I'm positive this will be like aerosols and asbestos, but we need to know where to start, perhaps even what to support as of right now.

  3. You guys deal with things that bring out the worst hysterics and fears in others on a daily basis. Are you doing ok? Because if you're not ok, then I just want to tell you we care about you and believe in you. We believe in a brighter future. Please don't give up.

ceropoint

1) There is now ample evidence that thawing frozen carbon is releasing methane. Globally and in our estimates, we assign a very small flux to it and believe that is not playing much of a role in the current spike. This could change in the future if global warming continues. Small fluxes changes are also attributed to frozen methane in coastal zones and oceans. 2) All options you cite are easy to implement and should all be addressed. Another option which are also important and feasible include flooding management in rice cultivation. A harder one is reducing emissions from livestock but recent findings show potential game changing practices in the way of feed supplements that block methane to be formed. See response further below. 3) Appreciate the comment. thanks


Hi, thank you for the research you're doing.

1) Having recently learned about the Clathrate gun hypothesis, how likely is the hypothesis now, taking into account your findings.

2) How do your findings alter current climate predictions? Do your findings mean we are on the way towards the RCP8.5 scenario?

Nikagda_nezabudem

1) We don't expect an abrupt increase in emissions from clathrates. Current knowledge suggests that we are likely to get a chronic but small flux, a flux that will might continue for hundreds of years and perhaps add up to something more significant in the end. Most clathrates are in the ocean, and we also know that most emissions will be oxidised and reach the atmosphere as CO2, not as CH4. That is good as CO2 is a less potent greenhouse gas.


What organizations that are fighting climate change would you recommend for donations?

Smartchoy

Rob Jackson: I won't recommend NGOs for donations. Three with which I've collaborated on research are the Environmental Defense Fund, the Union of Concerned Scientists, and National Resources Defense Council. EDF, for example, has led a major research effort to reduce methane emissions from oil and gas infrastructure.


Referring to this plot of methane concentration over time:

If you attribute the current rise in methane to tropical agriculture, what has changed in recent years vs. 2000-2010?

Why was methane rising so fast in the 1980s?

Thanks for taking these questions, and thank you for your work on this very important problem!

descabezado

BP : One of the key clues in interpreting the growth of methane in the 1980s and the growth rate today comes from the isotopic signature (stable isotopes, not radioactive) of the carbon in the CH4 molecule. Today, we're seeing that the increase in methane is associated with a lighter isotope of carbon, whereas in the 1980s, the isotope was heavy. The lighter isotope indicates the source is biological (either from agriculture or wetlands) and the heavy isotope is related to fossil fuels. Thus we know in the 1980s, fossil fuels drove the atmospheric methane increase, whereas in the past decade, biological processes most likely drove the increase.


The recent release of Before the Flood has placed a lot of attention on the agriculture industry for it's contributions to GHG emissions. I often see agriculture being blamed for about 1/3 of global emissions, with blame largely placed on cattle who release methane during digestion and require land to grow feed crops. How accurate is that statistic, and how do livestock compare to other agricultural sources of methane like paddy rice?

Edit: If you have time to look at this Redditor's quick analysis of Before the Flood's stats, could you please comment on his criticisms?

stubby_hoof

Rob Jackson: About 60% of global methane emissions come from human activities. Of those, a little more than half come from the agriculture and waste sectors. So your number of "about 1/3" is about right.


The recent release of Before the Flood has placed a lot of attention on the agriculture industry for it's contributions to GHG emissions. I often see agriculture being blamed for about 1/3 of global emissions, with blame largely placed on cattle who release methane during digestion and require land to grow feed crops. How accurate is that statistic, and how do livestock compare to other agricultural sources of methane like paddy rice?

Edit: If you have time to look at this Redditor's quick analysis of Before the Flood's stats, could you please comment on his criticisms?

stubby_hoof

BP: We have high confidence in the magnitude of the estimates of methane emissions from livestock and rice cultivation. Our study estimates livestock-related methane emissions as ~100 TgCH4 and rice cultivation 30 TgCH4, about 1/4 of global emissions.


Are termites still a major contributor? Has their impact/effect changed in scope? Has climate change increased their number/range?

sutree1

Rob Jackson: They are. Termites give off an estimated 10 Tg (1012 g) of methane a year. That's 1 or 2% of the global methane budget and comparable to the amount emitted from biofuel burning. Our data aren't great, though. Shockingly, there aren't too many methane termite specialists on the planet.


Are termites still a major contributor? Has their impact/effect changed in scope? Has climate change increased their number/range?

sutree1

Pep Canadell. Termites are regionally important as sources of methane, e.g., Australia and other subtropical regions and savannah. However, globally their contribute to less than 3% of the total natural emissions which are dominated by emissions from wetlands in the tropics and cold regions of the north.


Mostly a question for Mr. Poulter. Are you concerned about the incoming Trump administrations attitude towards climate change and what it means for your research? Trump has said he wants to cut down NASA climate research efforts. What does this mean for your work?

shreditorOG

BP : One of the advantages of working at NASA is that its an apolitical organization whose mission is basically to explore and understand the Universe - very cool. The scientific and technological innovations made by NASA have been critical for a wide range of reasons. Future leaders know that NASA provides essential resources, and inspiration, for humanity.


Mostly a question for Mr. Poulter. Are you concerned about the incoming Trump administrations attitude towards climate change and what it means for your research? Trump has said he wants to cut down NASA climate research efforts. What does this mean for your work?

shreditorOG

Rob Jackson: Ben gets the last word here. If the new administration guts the earth observing capabilities NASA has developed, we'll all be worse off. From tracking deforestation in Brazil to mapping the extent of sea ice, NASA satellites are critical for understanding the health of the earth.


Do you think there is scope for optimism? Will the Paris Agreement be able to atleast help limit emissions or is it too late?

How much increase in temperature will cause the permafrost to melt? Are there any ways to control its melting once it starts?

Are_kya_nam_rakhoo

RJ: There is always scope for optimism, and in this case there's good scope/hope. The Paris Accord is a good start. Eventually we'll need more, but that's OK.


Do you think there is scope for optimism? Will the Paris Agreement be able to atleast help limit emissions or is it too late?

How much increase in temperature will cause the permafrost to melt? Are there any ways to control its melting once it starts?

Are_kya_nam_rakhoo

Pep Canadell. it is never too late in climate change as it can always be worse. We don't have a good understanding of potential thresholds or points of no return, which probably are associated with ice dynamics. The paris agreement provides a very powerful tool for focusing on the long term of stabilisation temperature while meeting shorter term emission reductions, the first one in 2030. Current warming in the high latitudes is already leading to thawing permafrost and emissions to the atmosphere. We estimate it is a very small flux now which will increase in the future. Some of the emissions will be offset by increased woody encroachment and longer growing seasons, but ultimate there will be more emissions than increased sinks. The current possible range of emissions using future worst warming scenarios is between 50 and 200 billion tonnes of carbon during the decade. Even the lower bound is a very large amount of carbon. Current fossil fuel emissions are 10 billion tonnes per year.


In the editorial, you mention several options for mitigating methane emissions:

These opportunities include (i) venting and flaring of methane in coal-mines, while also improving worker safety, (ii) detecting and removing natural gas leaks, from wellpads upstream through the distribution chain downstream (e.g., McKain et al 2015), (iii) covering landfills, which reduces methane emissions while producing biogas for energy and transport usage, and (iv) developing farm bio-digesters, which has been extensively applied in Germany and is spreading to other European countries (e.g., Lebuhn et al 2014).

Of these, which would have the most significant impact on CH4 emissions? Which is the most likely to be implemented in the United States? Are these solutions also viable in developing countries?

shiruken

In the US, California recently passed a law to reduce CH4 emissions from agriculture and the Bureau of Land Management also passed a ruling for reducing methane from energy activities (https://www.doi.gov/pressreleases/interior-department-announces-final-rule-reduce-methane-emissions-wasted-gas-public).

Most likely, regulations need to address all sources, or pieces of the pie, to be effective. But the California and BLM rulings show action is happening.


In the editorial, you mention several options for mitigating methane emissions:

These opportunities include (i) venting and flaring of methane in coal-mines, while also improving worker safety, (ii) detecting and removing natural gas leaks, from wellpads upstream through the distribution chain downstream (e.g., McKain et al 2015), (iii) covering landfills, which reduces methane emissions while producing biogas for energy and transport usage, and (iv) developing farm bio-digesters, which has been extensively applied in Germany and is spreading to other European countries (e.g., Lebuhn et al 2014).

Of these, which would have the most significant impact on CH4 emissions? Which is the most likely to be implemented in the United States? Are these solutions also viable in developing countries?

shiruken

Pep Canadell. All these options are very good and need to be done all. Different regions will favour some options over others and that is why it is important to have a broad portfolio. Technically, they are all well established and make economic sense in most cases even in the absence of economic incentives.


Recently some of my friends (physicists) pointed out that absorption in CO2 band in atmosphere is already pretty much saturated. E.g. whatever CO2 can absorb it already absorbs and re-radiates. It means that more CO2 doesn't cause more global warming. Quoting them:

Absorption of IR light is already saturated at given CO2 concentration and can't increase much more to create more greenhouse effect. We are looking on a graphs like one on the page 5 and 7 here, showing that CO2 is already absorbing max in it's bands http://irina.eas.gatech.edu/EAS8803_Fall2009/Lec6.pdf

Is this correct understanding, or something is missing in this logic?

michwill

Pep Canadell. My understanding is that the band is getting saturated but CO2 emissions well pass mid century will continue to have a positive effect on the radiative balance.


Recently some of my friends (physicists) pointed out that absorption in CO2 band in atmosphere is already pretty much saturated. E.g. whatever CO2 can absorb it already absorbs and re-radiates. It means that more CO2 doesn't cause more global warming. Quoting them:

Absorption of IR light is already saturated at given CO2 concentration and can't increase much more to create more greenhouse effect. We are looking on a graphs like one on the page 5 and 7 here, showing that CO2 is already absorbing max in it's bands http://irina.eas.gatech.edu/EAS8803_Fall2009/Lec6.pdf

Is this correct understanding, or something is missing in this logic?

michwill

BP : Take a look at the climate primers at Real Climate http://realclimate.org/index.php/archives/2007/05/start-here/


To my understanding your observations and recent observations of significant increases in arctic methane emissions due to softening and melting permafrost seem very likely to correlate closely, to say the least.

Can you elaborate on why your research is focusing on other possible major contributing factors to the observable CH4 emission spikes of recent years, like certain dynamics in the tropics and in agriculture for example?

orbitalelements

Pep Canadell. There is a lot of work in measuring CO2 and CH4 emissions from thawing permafrost regions of the north, and measures have shown that old organic matter is being respired by micro-organisms. However, at the global scale we don't find those emissions to be large enough to drive the type of large changes in atmospheric CH4. In fact, we estimate those at present to be less than 1% of the total emissions while we have other sources such as wetlands, fossil fuels, and agriculture which are dominant sources many times larger than permafrost emissions. Having said that, emissions from the arctic are likely to increase in the future if warming continues at current pace.


Do you have ideas how we can potentially combat the new methane?

Also, I am very worried. I am 19 years old and will potentially live long enough to die due to climate change or see a radically altered world.

_AGermanGuy_

BP : Stay positive! There are lots of reasons for hope and for progress in tackling climate change, and you are in good company! Try to engage with businesses, organizations, fields of study, where your values are reflected and your time well spent.


Are we doomed as a human race or is there a solution?

Jamoz330

Rob Jackson: No way. There are real solutions. Some of them also save water and cut air pollution, saving lives in turn. They should be our priorities.


Has the clathrate gun fired?

Over the next few decades, where do you anticipate the best/worst places to live will be? (In terms of not becoming a climate refugee.)

PM_UR_PLATONIC_SOLID

Pep Canadell. Short answer is not and current knowledge suggests that we shouldn't expect for an abrupt and large release of methane from frozen methane largely in costal and deep ocean. However, there are emissions associated with coast erosion exposing frozen methane, something that has been happening since the end of the last glacial period. It is difficult for us to know whether any of the current background emissions are indeed the result already from human induced warming.


The rise in atmospheric methane seems to have accelerated in 2014 and 2015. What are the major causes?

How much methane monitoring is based on American institutions and policy?

Imhotep_Is_Invisible

BP : Yes, this is correct, the rise abruptly doubled in 2014 and 2015 compared with the previous 2007-2013 period. The 2014-2015 rise appears to be from a biological source that is tropical in origin, agriculture is likely responsible (livestock and rice production).

The monitoring of CH4 is done by ground stations, airplane campaigns, and also satellite. Each method has its shortcomings and advantages - satellite-based techniques are very promising so we can have global and daily observations. Just last week, NASA approved the GEOCARB mission to measure CO2 and CH4, and so the future looks good for monitoring methane more effectively!


Do you guys think that the type of seaweed that drastically reduces the methane emitted by cows could be the next big step to fighting the surge in methane?

Here's an article talking about it: http://www.abc.net.au/news/2016-10-19/environmental-concerns-cows-eating-seaweed/7946630?pfmredir=sm

AccountAttempt2

The dramatic reduction of methane from those caws being fed seaweed surprised everyone. It is unclear how we go about producing so much concentrated seaweed to make a global difference. The good news is that some plant oils have been found to have similar effects so it might be possible to have a variety of food supplements that enable a global deployment. The economics of it have not been worked out yet.


Don't you think the 20 year time horizon of CH4 is more important since the world is trying to keep warming to 1.5? It seems to me if we respond to methane based on it being 28X more powerful then we're going to overshoot. Because we could easily reach 1.5 in 20 years and over a 20 year time horizon methane is 86X more potent than CO2.

WowChillTheFuckOut

BP : the choice of the timeline to use as the global warming potential in an active area of debate. In the context of temperature targets, one policy theme is based around the 'two targets' idea, where the one target takes a long-term, e.g. 100-year, point of view where CO2 mitigation is essential, and the other takes a 25-year point of view where CH4 mitigation is essential for keeping climate change below 1.5 or 2.0 degrees warming. For more info, see http://www.ccacoalition.org/zh-hans/file/2484


Hello, I am a atmospheric researcher at Indiana University looking at soil fluxes of NOy. My question is less about your findings and more about the future of our research. I was planning on applying for post doctoral work at a national laboratory in hopes of continuing research in my area. We are already starved for funding as it is and are worried that we may be entering a hostile landscape for continued research in this area. Without getting into politics, I was wondering how you plan on transitioning (assuming there will be cuts in climate related research) and what this means for upcoming environmentally focused graduate students like myself?

randomways

Rob Jackson: Stay the course. We'll may need to change some of the research we do, and change what we call some of our research. As I stated above, though, cutting greenhouse gas emissions can save water, reduce air pollution, and save lives. That's something everyone can relate to regardless of background or political persuasion.


How do methane hydrates rate as a concern compared to other sources? What is the latest research on climate change affecting the possibility of increased release of hydrates?

wtf_yoda

Pep Canadell. Methane hydrates or clathrates are frozen methane in permafrost regions on land, but mostly on coastal areas and deeper in the ocean. Current knowledge suggests that we won't have an abrupt release of methane emissions from this source but we could see some unwanted releases from hydrates on land as permafrost thaws. It would take a lot of warming of hundreds of years before we can reach deep hydrates in the ocean and warming them enough to be released. Even in that case, we would expect that most of the methane would reach the atmosphere as as CO2, not CH4 (it would oxidised in the ocean). In any case, any new chronicle even relatively small new source of methane/CO2 will make climate stabilisation a harder objective.


Could genetically modifying flood crops such as rice reduce methane production?

Dragoarms

Rob Jackson: Breeding rice that needs less flooding can make it more drought tolerant and reduce methane emissions. Both things are good. The trick is not to lose too much productivity.


https://en.wikipedia.org/wiki/Methanotroph

will these guys save the game?

axis_of_elvis

RJ: Methanotrophs in soils consume about 30 Tg (1012 g) of methane per year. They're an important sink for methane destruction, but OH radicals in the atmosphere are far more important. It all helps, though.


Is there any chance of future tech reversing the damage done completely and quickly?

Tatanka10010413

BP : Methane is classified as a 'short-lived climate pollutant' meaning that actions taken today to reduce emissions would be noticed within about a 10-20 year time frame. So yes, 'quickly' is possible if we implement technological fixes.


I recently read that a study found that introducing a small amount of dried seaweed into cattle feed reduces their enteric methane gas production by up to 99%. Given that livestock is such a significant source of atmospheric methane, why is this not more in the news? I would expect this to be universally adopted within months of the discovery.

doctorcurly

RJ: The work was done in Australia and is pretty new (http://www.abc.net.au/news/2016-10-19/environmental-concerns-cows-eating-seaweed/7946630). I don't know much about it, frankly. Some next steps are to test it in other places and to consider the economic costs.


There have been reports of seaweed added to bovine feed reducing methane emissions dramatically. Is this something you can comment on?

PhrankLee

Pep Canadell. yes, and seaweeds are not the only feed supplements that have been found to reduced methane emissions in livestock. However, the findings are still at the level of research and development to ensure that it is a long term effect and that there are no side effects. Perhaps most importantly, the research is far from understanding the type of economic model that could make the supplements globally and a low price to be uptake by farmers and industry.


How can I convince people that climate change is a real phenomenon?

penguin8r

Continue to educate yourself on climate change! Invite a climate scientist from Climate Voices http://climatevoices.org/ to give a lecture at your school, work, bookstore, church ...


  1. Aside from being a greenhouse gas, does methane have secondary effects? For example, CO2 contributes to ocean acidification, and fossil fuel particulates lower air quality, especially in developing nations like China.

  2. What's your take on how we balance the long term effects of methane output with the potential benefits? It's easy for us to say we need to reduce agricultural output, but that may mean removing a food source from people who need it in the developing world. We have to balance both an obligation to protect the planet (And it's people) in the long term with an obligation to protect people in the short term (starvation, weather, health, etc). I'm with you guys - the long term effects of climate change seem likely to be devastating on a scale different from the effects of reducing them, but where do you see that line?

ocean_sadification

BP: (1) Methane is a precusor to tropospheric ozone, meaning that when methane reacts with NOx, ozone is formed. Ozone is dangerous to both humans, and also to plants. Ozone damages photosynthetic chemistry and leaf functioning, and a lot of work has shown how crop yields decline with high ozone concentrations. Reducing CH4 not only mitigates climate but has substantial human and ecosystem health benefits.


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